Restless, shallow magma under Iceland's tremor-jolted fishing town of Grindavik on Iceland's western Reykjanes peninsula has left residents robbed of sleep in a volcanic zone dormant for the past 800 years.

Some have retreated to hotels in the capital Reykjavik, some 30 kilometers (18 miles) away, to recuperate while geophysicists continue to warn that an eruption could be imminent.

If so, experts believe it's likely to an eruption of mainly lava — unlike the massive ash cloud generated by the 2010 Eyjafjallajökull volcano which disrupted around 900,000 flights across Europe.

Since February 24, Grindavik and the peninsula's Krysuvik volcanic system, an otherwise larglely uninhabited zone that includes Mount Keilir, has recorded 40,000 tremors as hefty as magnitude 5.7.

"Everyone here is so tired," Grindavik school teacher Rannveig Gudmundsdottir told Reuters. "It's like you're walking over a fragile suspension bridge."

Unusual level of activity

Grindavik had in human memory never witnessed so much seismic activity, according to volcanic hazards coordinator Sara Barasotti of Iceland's IMO weather institute.

Molten rock 1 kilometer below the surface was likely to have risen 8 to 10 kilometers from a lower magma chamber, said Thorvaldur Thordarson, a University of Iceland volcanologist.

"That's very shallow," he said. "How long does it take [for an eruption to follow]? We don't know." But, if there were an eruption, he said, it would be a burst of lava, not much ash.

Tectonic clash zone

Iceland straddles the clash zone between the Eurasian and North American tectonic plates and experiences an eruption roughly every five years.

In 1973, fountains of lava surprised inhabits of the island Heimaey, spewing from a fissure just 150 meters from the town center.

In June last year, experts warned that Iceland's most active volcano, Grimsvotn, was about to erupt under a glacier, but so far that has not happened.

ipj/msh (AFP, Reuters)